I wouldn't use copper in the DR because it's very prone to corrosion in the topics and nowadays copper has gotten stupid expensive. I'd go with high temp PEX pipe if I could find it.
Here is one DIY system using PEX. Looks pretty straight forward. You could lay PEX under some standard corrugated roofing over some insulated boards. One of the big pluses of PEX is there is no sweating pipes for the elbows, which you need A LOT of for copper.
Construction of PEX Solar Collector
When I built a solar water heater before(like 30 years ago in a high school project), we used check valves to get the water to cycle through the storage tank. A small (solar powered) aquarium pump would prob to the job as well.
Here is one DIY system using PEX. Looks pretty straight forward. You could lay PEX under some standard corrugated roofing over some insulated boards. One of the big pluses of PEX is there is no sweating pipes for the elbows, which you need A LOT of for copper.
Construction of PEX Solar Collector
When I built a solar water heater before(like 30 years ago in a high school project), we used check valves to get the water to cycle through the storage tank. A small (solar powered) aquarium pump would prob to the job as well.